The present invention relate to a passenger compartment monitoring apparatus, and more particularly to a monitoring apparatus that can be installed in both right-hand and left-hand drive vehicles to optimally monitor a passenger compartment of the vehicle.
A passenger compartment monitoring apparatus that prevents the operation of an air bag device under certain conditions is know in the art. The monitoring apparatus includes a CCD camera and a computer that are arranged in the passenger compartment. The computer analyzes images of the passenger compartment that are taken by the CCD camera and prohibits operation of the air bag device under certain conditions based on the analysis result. For example, in a passenger compartment monitoring apparatus disclosed in Japanese Laid-Open Patent Publication No. 2000-264128, since the CCD camera is arranged in a passenger compartment that is limited in space, a reflection mirror of a room mirror is used as a half mirror. The CCD camera is incorporated between the half mirror and a case. The half mirror is used to view a passenger seat. For example, when a child seat is mounted on the passenger seat, the operation of an air bag device is prohibited under certain conditions.
However, in the passenger compartment monitoring apparatus of JP2000-264128, the CCD camera is capable of monitoring the passenger seat of only a right-hand drive vehicle or only a left-hand vehicle. The imaging area of the CCD camera installed in a right-hand drive vehicle differs from that of the steering wheel installed in a left-hand vehicle. Therefore, two types of monitoring apparatuses must be manufactured, one for right-hand drive vehicles and another for left-hand drive vehicles. Thus, it takes time to manufacture the passenger compartment monitoring apparatuses.
It is an object of the present invention to provide a passenger compartment monitoring apparatus that obtains the necessary monitoring area regardless of whether the monitoring apparatus is installed in a right-hand drive vehicle or a left-hand vehicle.
To achieve the above object, the present invention provides a passenger compartment monitoring apparatus including a room mirror arranged in a passenger compartment. A plurality of imaging devices are arranged in the room mirror. Each of the imaging devices is arranged at a predetermined angle with respect to the room mirror so as to monitor a predetermined area of the passenger compartment when arranged in either one of a right-hand drive vehicle or a left-hand drive vehicle.
A further perspective of the present invention is a passenger compartment monitoring apparatus including a rotatable room mirror arranged in a passenger compartment. First and second imaging devices are arranged on the room mirror. The first imaging device has a first horizontal angle of view and a first vertical angle of view and the second imaging device has a second horizontal angle of view and a second vertical angle of view. When the room mirror is arranged so that a normal line with respect to the room mirror lies on a horizontal plane of the vehicle, the first imaging device has a first horizontal mounting angle formed by a first horizontal projection optical axis that is obtained by projecting an optical axis of the first imaging device on the horizontal plane and a horizontal reference line that is vertical to the normal line on the horizontal plane. The first horizontal mounting angle is set based on the first horizontal angle of view and a rotation angle of the room mirror that faces a driver seat. The second imaging device has a second horizontal mounting angle formed by a second horizontal projection optical axis obtained by projecting an optical axis of the second imaging device on the horizontal plane and the horizontal reference line and the horizontal mounting angle is set based on the second horizontal angle of view and the rotation angle. The first imaging device has a first vertical mounting angle formed by a first vertical projection optical axis obtained by projecting the optical axis on the vertical plane and a vertical reference line that is vertical to the normal line on the vertical plane. The first vertical mounting angle is set based on the first vertical angle of view. The second imaging device has a second vertical mounting angle formed by a second vertical projection optical axis obtained by projecting the optical axis on the vertical plane and the vertical reference line. The second vertical mounting angle is set based on the second vertical angle of view. The first and second horizontal angle of views are set so that imaging areas of the first and second imaging devices are overlapped with each other at a predetermined distance from the room mirror.
Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.